Sutures are commonly used for closing wounds and/or surgical site incisions, or to repair tissue that has torn. When using a suture, it is important to avoid infection. Although surgeries and wound closings are often performed under sterile conditions, surgical site infections (SSIs) are the third most commonly acquired hospital infection, and may be associated with severe morbidity and mortality. Since more than sixty percent (60%) of SSIs occur in the area of the incision, the use of sutures having antimicrobial properties has the potential to be useful in combating such infections and, ultimately, improving patient outcomes by reducing the amount and severity of these SSI-type infections.
Sutures having antimicrobial properties currently exist. At the present time, the industry leader in the antimicrobial suture market is Ethicon, a Johnson & Johnson company. Johnson & Johnson's Ethicon antibacterial sutures rely primarily on a Triclosan-type antimicrobial agent.
Triclosan is a chlorinated phenolic biocide antiseptic that, according to Johnson & Johnson, has a different mode of action than traditional antibiotics. It is a “phenol” with multi-targeted biocidal mechanisms that are believed to have non-specific effects that act on cell membrane activities to kill undesired microbes. It is also believed that Triclosan blocks the active site of the Enoyl-acyl carrier protein reductase (ENR) that is an essential enzyme in fatty acid synthesis, used in building cellular components and in cell reproduction.
Ethicon's Triclosan-coated sutures appear to be able to perform their antimicrobial function in a manner similar to counterparts that do not contain Triclosan. To date, published data exists to suggest that Triclosan inhibits bacteria colonization of a suture. See, Ford H R, Jones P, Reblock K, Simpkins D L, “Intra-operative Handling and Wound Healing Characteristics of Coated Polyglatin 910 Antibacterial Suture and Coated Polyglactin 910 Suture”. Surg. Infec. 2005; 6; 313-21.
Additionally, an in vivo study of Ethicon's Triclosan-coated sutures (i.e., Ethicon's VICRYL Plus™ antibacterial sutures) showed that they have an inhibitory or bactericidal activity against Staphylococcus aureus, Methicillin-Resistant S. Aureus (MRSA), S. Epidermidis (Biofilm-Positive) and E. coli. See, Storch M L, Rothenberger S J, Jacinto G, “Experimental Efficacy Study of Coated VICRYL+Antibacterial Suture in Guinea Pigs Challenged with Staphylococcus Aureus”. Surg. Infect. J. 2004; 5; 2A1-288.
Additional information about Ethicon's Triclosan-coated sutures can be found on Ethicon's web site at http://www.plussutures.com. Additional discussions of Ethicon's antimicrobial sutures can be found in Stephenson, U.S. Pat. No. 4,024,871 (24 May 1997) and Scalzo et al., U.S. Pat. No. 7,513,093 (7 Apr. 2009). In particular, the reader's attention is directed to the prior art discussions in each of these Ethicon patents, as a wide variety of various antimicrobial agents and methods for incorporating antimicrobial agents into sutures are discussed therein.
The Tyco Healthcare Group of Covidien plc has also been active in the antimicrobial suture field. An example of a Tyco antimicrobial suture is discussed in Robey, U.S. Pat. No. 6,878,757 (12 Apr. 2005), which discloses an antimicrobial suture coating that contains a fatty acid ester salt mixed with a bioabsorbable co-polymer.
Another Tyco antimicrobial suture patent application is Cohen, U.S. Patent Application Publication No. US2007/0010856 A1, published 11 Jan. 2007. Cohen's antimicrobial suture includes a plurality of filaments with interstitial spaces defined by the plurality of filaments, and an antimicrobial solution disposed within the interstitial spaces. An antimicrobial coating is placed on at least a portion of the plurality of filaments. The preferred antimicrobial agent used in Cohen is an antiseptic, film-forming polymer, and a salt of a fatty acid ester. Examples of the same are given in paragraph [0014] of the aforementioned published Cohen patent application.
Additionally, Polymedix, Inc. has developed an antimicrobial suture. The Polymedix suture employs PolyCide® polymers that are described as “novel defensin-mimetic compounds” which are synthetic mimetics of the host offense proteins that (according to Polymedix) are one of the oldest and most effective antimicrobial defense systems found in humans and virtually all living creatures. These PolyCides® are alleged to have a mechanism of action that directly disrupts the bacterial cell membranes and makes the development of bacterial resistance unlikely to occur. More information about these antimicrobial sutures can be found at www.polymedix.com. See also the Polymedix press release dated 11 Jun. 2010 “New Grant Supports Development of Antimicrobial Sutures to Combat Infection” (http://www.newswise.com/articles).
Silver is another compound having well known antimicrobial properties, and silver has been used to provide particular articles with antimicrobial properties. One early example of silver being used in a ligature is shown in Clark, U.S. Pat. No. 861,231 (23 Jul. 1907). Clark created a surgical ligature that was soaked in an antiseptic salt that preferably comprised an iodide of silver as the salt.
Another example of the use of silver to create an antimicrobial product is shown in Indiano, U.S. Patent Application Publication No. 2010/0000196, published 7 Jan. 2010. In Indiano, a textile product (non-suture related) incorporates silver to render the product antimicrobial.
Although the above-referenced products presumably perform their intended function, room for improvement exists. In particular, there is a need for a novel antimicrobial suture that is both capable of having significant antimicrobial properties and that can be produced at a reasonable cost, to provide a cost-effective deterrent to infections.